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java

Posted by dihan on July 18, 2001 at 12:36 AM

> I am trying to create a servlet that serves as a broker within a 'web services' model.
> For example - there exists a web service that upon receiveing the correct HTTP GET request, in XML format, it will return to me a JPG formatted image of my choice. My servlet actually receives a request first, as its the real client app, but if I don't have that image I go and get it from this external web service.

> An example GET request that I'll generate to send out to the service might be:
>
> String XMLRequest= ""

> I send this string using a simple URLConnection Object, for example:

> URL url = new URL("http://10.3.1.56/imageserver.asp");
> URLConnection connection = url.openConnection();
> connection.setDoOutput(true);
> PrintWriter out1 = new PrintWriter(connection.getOutputStream());
> out1.println(XML_Request);
> out1.close();

> Now I want to get my response off that connection:

> BufferedInputStream in = new BufferedInputStream(connection.getInputStream());

> The problem is that I do not always know what I will get back. If the image is unavailable or my request string is bad, I'll get an XML error message back...like:

> BufferedOutputStream out = new BufferedOutputStream(response.getOutputStream());

> Finally, I guess (low confidence here), I want to transfer the data from the 'in' buffer array to the 'out' buffer array and then do a out.flush(). Is that smart? I also thought to use the read(byte array) method like:

> while(in.read(out));

> but I get an error stating 'in' is not a buffer array. What?

>
> Question 1.) First theory. What combination of OutputStream classes should I use here so that if I get the image data back, I can forward it on to the response losing the least amount of time and processing/memory?

> Question 2.) Java documentation for BufferedInputStream states that it creates a buffered array..."When the BufferedInputStream is created, an internal buffer array is created." WHere is it?

> Question 3.) How should I work with transfering binary data from one buffer array to another? (Perhaps an example from question 1 makes this clear.) Does the flush write it out like I think it does?

> Question 4.) How should I deal with the fact, I may get two types of data back(binary or XML text) and its unknown when?

> I sincerely thank you for a response and will be happy to share results afterward.

> Regards,
> Chris Adams